Cardiopulmonary bypass is commonly used to maintain oxygen delivery to peripheral organs during cardiopulmonary arrest in a variety of cardiothoracic surgeries, septal defect repairs, heart valve repairs and replacement, aneurysm repairs, and corrections of congenital defects. Before cardiopulmonary bypass can be initiated, the heart and coronary blood vessels must be isolated from the peripheral vascular system. This is usually accomplished by arterial cannulation of the aorta and venous cannulation of the right atrium, inferior vena cava, or superior vena cava. Venous drainage catheters are commonly used to withdraw the deoxygenated blood from the right atrium, inferior vena cava, or superior vena cava, pass it to a bypass oxygenator machine, and the blood is thereafter returned to the patient's aorta.
Venous drainage catheters typically include at least one drainage port at the distal end. However, the walls of the organ or vessel within which the drainage ports are disposed will often close down around the drainage ports and thereby obstruct the flow of blood into the cannula. This difficulty will often prevent adequate drainage of blood to the bypass oxygenator machine. Thus, a need exists for an improved venous drainage catheter to prevent obstruction of drainage ports by adjacent tissues during operation.